The present invention relates to a water temperature control device for a cooling system with a reduced number of parts for circulating cooling water to a water pump through either a radiator or bypass line depending on the water temperature of the cooling water from the water jacket of an automobile engine, and which has improved thermostat sealing capability as well as means for preventing pellet assembly piston release.
In general, a cooling system of an engine comprises a water pump at an inlet side of a water jacket provided within cylinder head and cylinder block. A thermostat positioned at an outlet side of the water jacket is used as a water temperature control device. The water temperature control device detects the water temperature of the cooling water from the water jacket and controls the flow direction of the cooling water.
A conventional water temperature control system 100, as shown in FIG.3, is assembled with a case main body 101 and a case cover 102. The case main body 101 includes a cooling water inlet 103 connected to the outlet of the water jacket, and a bypass outlet 104 for passing the cooling water to the water pump. The case cover 102 includes a cooling water outlet 105 for supplying the cooling water to a radiator.
A thermostat 106 is mounted to the case main body 101. The thermostat comprises a dome type seat 109 supported by a seal portion 108 with a sealing member 107 interposed between the case main body 101 and the case cover 102. A valve means 112, elastically supported by a spring 111 to a frame 110, is located within interior of the case main body 101. A piston 113 extending from a pellet assembly 114 is positioned in a recessed portion 109a of the dome type seat 109.
With the conventional water temperature control system 100, the thermostat 106 opens and closes in response to the water temperature of the cooling water by the forcing of the piston 113 out of the pellet assembly 114 and against the recessed portion 109a. This approach, however, has resulted in the release of the piston 113 from the recessed portion 109a due to vibration from the water pressure and the like, degrading the sealing characteristics of the thermostat 106. Moreover, the assembly of the device is difficult because the conventional water temperature control device has numerous parts.